If you don't have your iPhone, but your Apple Watch is working, you can erase all content and settings on your Apple Watch. On your Apple Watch, tap Settings > General > Reset > Erase all Content and Settings. For Apple Watch Series 4 (GPS + Cellular) or Apple Watch Series 3 (GPS + Cellular), tap Erase All to remove your plan.

Remove your Apple Watch band

Send in your Apple Watch

Now your device is ready to send in for repair. If you arranged a repair request, you should have received instructions for how to mail in your device. If you already received a replacement Apple Watch, follow these steps to set it up.